Out of the Israelis’ conflict with Palestinians in the Gaza Strip, at least one success story has emerged: Israel’s Iron Dome counter-rocket system. With 735 interceptions of rockets and mortar bombs, Iron Dome demonstrated improved performance, scoring an almost 90% success rate.

Of 4,594 rockets and mortars fired from the Gaza Strip in 50 days of conflict, Iron Dome failed to intercept only 70 rockets where the system was deployed. One Israeli civilian was killed by a rocket, three other civilians and nine servicemen were killed by mortars, but there were no fatalities in the areas protected by the Iron Dome. The operational results appear to contrast with an ongoing academic debate in the U.S. about the system’s efficacy.

“This is an unprecedented and significant strategic achievement,” Israeli Defense Minister Moshe Ya’alon told Aviation Week. “Iron Dome almost negated Hamas’s [the Islamic Resistance Movement’s] medium- and long-range capabilities,” added a senior Israeli air force officer. “Those 735 rockets intercepted represent dozens of Israeli casualties whose lives were saved.”

Foreseeing the conflict, Israel deployed its six batteries of Iron Dome around urban centers in the days prior to launching its offensive into Gaza, dubbed “Operation Protective Edge,” on July 8. In the following days, Rafael Advanced Defense Systems, Iron Dome’s developer and main manufacturer, delivered three just-completed additional batteries. With nine batteries deployed and with thousands of intercepting missiles, Israel’s main cities were ready to meet the shower of rockets launched by Hamas and the Palestinian Islamic Jihad (PIJ) from Gaza. During the fighting, a 10th battery was delivered but not deployed, due to shortage of qualified staff.

On the Palestinian side, Hamas and PIJ amassed 9,000 rockets, mostly short-range 107-mm types. The arsenal includes about 1,000 122-mm rockets with a range of 45 km (28 mi.) and about 200 M75 8-in. rockets with a range of 75 km. The Palestinian forces also possess several dozen indigenous versions of Syrian 302-mm rockets, dubbed R160, with a range of more than 100 km.

Only a small part of that stockpile were standard serial-production rockets smuggled into Gaza from Egypt. Since the Egyptian army, headed by Abd Al-Fatah A-Sisi, took rule of the country in July 2013, Egypt has destroyed most of the smuggling tunnels dug from its territory into Gaza. As a result, the Palestinian militant organizations had to resort to improvised indigenous production of rockets and mortars.

Those improvised rockets demonstrated low accuracy and an unstable trajectory, sometimes confusing the operators of the Iron Dome, who intercept only the rockets threatening to strike populated areas. “We shortly realized we cannot trust the Palestinian rockets to perform a standard ballistic trajectory,” says Yossi Drucker, director for Air Superiority Systems at Rafael.

Out of the vast number of rockets fired, only 25% were effective and threatened to hit populated areas, a recurring ratio in previous conflicts with Gaza or Lebanon. That allowed Iron Dome to disregard most of the rockets. In most interceptions, a single “Tamir” interceptor was launched against each incoming rocket. In cases where the rockets were aimed at more densely populated areas, two interceptors were allocated, each with a cost of $50,000.

While Iron Dome could be operated in a fully automated mode, the air force has chosen to operate it in a man-in-the-loop mode, requiring the operators to decide within a few seconds whether and how to intercept. That policy proved to be effective, allowing most of Israel to maintain normal life with minimal interference. One operator’s error, however, disrupted international air traffic to Israel for up to a day and a half.

Throughout the conflict, Hamas made an effort to strike Israel’s Ben-Gurion International Airport. On July 22, as a rocket was fired at the airport, the Iron Dome operator decided not to intercept it, fearing that the interception might jeopardize civilian aircraft that were approaching for landing. The rocket landed 1 mi. away from the airport, and hours later the FAA ordered U.S. airlines to halt flights to Israel. A number of European airlines followed and canceled flights to Tel Aviv.

In response, Israel rushed to reassure American and European authorities that the rocket fire and Iron Dome activity posed a “negligible” threat to civil aviation. “Based on an [Israeli air force] study, the chance of an aircraft flying in Israeli airspace being hit by a random rocket fired from Gaza is one in a billion,” said Giora Rom, head of Israel’s Civil Aviation Authority (ICAA), in a letter sent to all international aviation authorities. In addition, ICAA has rerouted incoming and outgoing air traffic from Ben Gurion into corridors separated from the area where Iron Dome operates. All airlines resumed flights to Israel after 36 hr., with the exception of Korean Air.

“Without passing judgment on the Iron Dome operator’s decision, the system could have intercepted this rocket without posing any risk to air traffic,” says Drucker. “The system is designed to operate in the presence of air traffic. The chances of an Iron Dome interceptor hitting an aircraft are even smaller than the chances of an aircraft being hit by an incoming rocket.”

Iron Dome’s success against medium- and long-range rockets did not slacken Palestinians’ attempts to strike Israel. But as the Palestinians’ stockpile diminished, they started directing most of the fire against the villages bordering Gaza, where Iron Dome is not deployed. Even there, Iron Dome managed to intercept, for the first time, 10 mortar bombs fired at the town of Sderot.

While the success of Iron Dome was evident in the small number of losses and damage to the Israeli rear, some critics continue to claim that Iron Dome fails in most interception attempts. The most notable is Massachusetts Institute of Technology physicist Ted Postol, who presented a study claiming that Iron Dome succeeds in only 5% of interception attempts. 

“These allegations are ludicrous,” says Uzi Rubin, former director of Israel’s Missile Defense Organization.  “If it was true, how come that after 4,000 rockets fired at Israel there are no fatalities in the areas protected by Iron Dome? A similar number of rockets were fired by Hezbollah during the 2006 war in Lebanon—and then, without the Iron Dome, there were scores of Israeli casualties.”

The system received another vote of confidence in the U.S. Congress, which approved an additional $225 million funding for Iron Dome on Aug. 1. The budget is directed toward restocking Iron Dome interceptors and brings U.S. funding for the system to a total of $1.3 billion. 

But there is also a curse in the Iron Dome’s success, as a senior defense source put it: “It creates an image where the Israeli side appears unharmed and makes it much harder to explain to the world why we fight.”